Embodiments of the present disclosure generally relate to common mode traps, for example common mode rejection cables for magnetic resonance imaging (MRI) systems.
MRI is a medical imaging modality that generates images of the inside of a human body without using x-rays or other ionizing radiation. MRI or Nuclear Magnetic Resonance (NMR) imaging generally provides for the spatial discrimination of resonant interactions between Radio Frequency (RF) waves and nuclei in a magnetic field. Typically, an MRI system includes a superconducting magnet that generates a main magnetic field within an imaging volume. The MRI system uses various types of radio frequency (RF) coils to create pulses of RF energy. The RF coils transmit RF excitation signals and receive magnetic resonance (MR) signals that the MRI system processes to form the images.
Coil interfacing cables may be used to transmit signals between the RF coils and other aspects of the processing system, for example to control the RF coils and/or to receive information from the RF coils. The coil interfacing cables may be disposed within the bore of the MRI system and subjected to electro-magnetic fields produced and used by the MRI system. The cables may support transmitter driven common mode currents which create field distortions and/or unpredictable heating of components. Conventionally, baluns or common mode traps that provide high common mode impedances may be utilized to mitigate the effect of transmitter driven currents. However, placing the common mode traps or blocking circuits at appropriate locations may be difficult, as the appropriate placement may vary based on the positioning of a cable or coil associated with the common mode traps. Also, excessive voltage and/or power dissipation may occur even if conventional common mode traps or blocking circuits are placed at appropriate locations. Further, adding additional conventional discretely located baluns or common mode traps may be unwieldy and/or cost prohibitive.